Chiari Malformation

Chiari malformation is a rare condition in which brain tissue is forced downward into the spinal canal because part of the skull is abnormally small or misshapen. There are four types of Chiari malformation:

  • Type I develops as the skull and brain are growing, disrupting the normal pulsation of cerebrospinal fluid. Symptoms may not occur until late childhood or adulthood.
  • Type II is the most common pediatric form and is present at birth. The spinal cord and column fail to close properly during fetal development, causing an open spinal cord defect.
  • Type III involves a portion of the cerebellum and/or brainstem pushing out through a defect in the back of the head or neck. This form is very rare and is associated with a high early mortality rate or severe neurological deficits.
  • Type IV is the most severe form and the rarest. The cerebellum fails to develop normally, and survival is rare.

Making a Difference Through Surgery

At North Texas Neurosurgical & Spine Center, we specialize in the treatment of Chiari malformations using advanced decompression techniques under general anesthesia. To relieve symptoms and fluid filling the cavity in the spinal cord, we decompress nerve tissue and promote normal cerebrospinal fluid flow around and behind the cerebellum, which controls the coordination of motion.

Surgery on Type I Chiari malformations may involve only local decompression of the overlying bones, decompression of the bones and release of the dura (a thick membrane covering the brain and spinal cord), or decompression of the bone and dura and some degree of cerebellar tissue resection.

In this decompression surgery, we remove the back of the foramen magnum (the largest opening at the base of the skull through which the spinal cord enters and connects to the brainstem) and often the back of the first few vertebrae. A tissue graft is often spliced into this opening to provide more room for passage of cerebrospinal fluid.

Type II Chiari surgery is similar, but usually restricted to decompressing the tissues in the spinal canal and leaving the back of the skull intact.